If you are going with EFI down the road that would be the best time to activate the twin plugs since it will be a cheaper at that point. So if your pretty sure that EFI is in the future then machining the heads now would be a good idea.

In the meantime just be conservative with the boost on pump gas. If you have some track days putting in race gas will allow you to run higher boost. Maybe one of the gurus on the board can suggest the best timing settings for the different octane/ boost levels.